The present disclosure relates to the subject matter contained in Japanese Patent Application No. 2002-140935 filed on May 16, 2002, which is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to a technical field of a vehicular air conditioning control apparatus adopting an electric cooling fan of an external (variable capacity) control type in an air conditioning cycle.
2. Description of the Related Art
Conventionally, there is known a vehicular air conditioning control apparatus, as such described in JP-A-2000-274243.
In the publication, with an object of achieving necessary minimum operation of a cooling fan over an entire operating region, there is described an apparatus for controlling an electric cooling fan arranged on the back side of a condenser and a radiator by constituting reference parameters by vehicle speed, engine cooling water temperature and compressor discharge pressure and selecting a control constant from a cooling fan operation map in an ON state of an air conditioner of operating a compressor.
However, in controlling the cooling fan of the conventional vehicular air conditioning control apparatus, the compressor discharge pressure is referred only with an object of acquiring information of an operating situation of the air conditioner. Therefore, when the cooling fan is controlled similarly under all of the vehicular conditions, there poses a problem that a deterioration in fuel efficiency is accelerated under specific vehicle conditions (in cooling down and in idling).
That is, in cooling down requesting a high cooling performance, when load of the cooling fan is restrained in consideration of technical thought of achieving the necessary minimum operation of the cooling fan as described in the object of the prior art, in order to meet the request of the high cooling performance, load of the compressor is increased to a high level by an amount of restraining the load of the cooling fan.
Further, in idling requesting to maintain the cooling performance, when the load of the cooing fan is restrained in consideration of the technical thought of achieving the necessary minimum operation of the cooling fan as described in the object of the prior art, in order to maintain the cooling performance, the load of the compressor is increased. Further, in the idling, a function of cooling a condenser by running wind becomes deficient.
As a result, both in the cooling down and the idling, by an increase in the load of the compressor in accordance with restraining the load of the cooling fan, a total load of the engine, further, the total load of a battery represented by a total sum of the load of the compressor and the load of the cooling fan is increased to accelerate the deterioration in the fuel efficiency depending on the magnitude of the loads.
The invention has been carried out by paying attention to the above-described problem and it is an object thereof to provide a vehicular air conditioning control apparatus capable of achieving to improve fuel efficiency while ensuring a requested cooling performance in cooling down or idling.
In order to achieve the above-described object, according to one aspect of the invention, in a vehicular air conditioning control apparatus having a compressor and an electric cooling fan of an external (variable capacity) control type, a fan motor is controlled to increase load of the fan motor in a region of a delivery capacity of a compressor lower than that in normal control in any of below-listed cases.
(1) When it is predicted that a requested cooling performance is increased.
(2) When a vehicle is brought into an idling state.
(3) In cooling down when it is predicted that a requested cooling performance is increased to be equal to or higher than a predetermined value, or, when a vehicle is brought into an idling state.
Here, the normal control signifies a control of providing a load of a fan motor in accordance with a delivery capacity of a compressor to achieve better fuel efficiency in normal running in which running wind is introduced into a condenser and a requested cooling performance is not changed or changed by a small amount.
According to the vehicular air condition control apparatus of the invention, in cooling down or in idling, there is carried out cooperative operation in which in accordance with an increase in a load of a fan motor in a region of a low delivery capacity of a compressor with excellent response, an increase in the delivery capacity of the compressor is restrained to be low. As a result, while ensuring the requested cooling performance, a total engine load represented by a total sum of the load of the compressor and the load of the cooling fan is restrained to be low and an improvement in fuel efficiency depending on the total engine load can be achieved.